Selective atomic layer etching of semiconductor materials

ABSTRACT

Precursors, such as interhalogens and/or compounds formed of noble gases and halogens, may be supplied in a gaseous form to a semiconductor processing chamber at a predetermined amount, flow rate, pressure, and/or temperature in a cyclic manner such that atomic layer etching of select semiconductor materials may be achieved in each cycle. In the etching process, the element of the precursor that has a relatively higher electronegativity may react with select semiconductor materials to form volatile etching byproducts. The element of the precursor that has a relatively lower electronegativity may form a gas that may be recycled to re-form an precursor with one or more halogen-containing materials using a plasma process.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment.More specifically, the present technology relates to methods and systemsfor isotropic atomic or molecular layer etching of materials used insemiconductor processing.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers, or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess that etches one material faster than another facilitating, forexample, a pattern transfer process. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits, and processes, etch processes have been developedwith a selectivity towards a variety of materials.

Etch processes may be termed wet or dry based on the materials used inthe process. A wet HF etch preferentially removes silicon oxide overother dielectrics and materials. However, wet processes may havedifficulty penetrating some constrained trenches and also may sometimesdeform the remaining material. Dry etches produced in local plasmasformed within the substrate processing region can penetrate moreconstrained trenches and exhibit less deformation of delicate remainingstructures. However, local plasmas may damage the substrate through theproduction of electric arcs as they discharge.

Thus, there is a need for improved systems and methods that can be usedto produce high quality devices and structures. These and other needsare addressed by the present technology.

SUMMARY

Exemplary etching methods may include flowing a halogen-containingprecursor into a processing region of a semiconductor processingchamber. The methods may further include contacting an exposed region ofa semiconductor material with the halogen-containing precursor such thatthe halogen-containing precursor may be adsorbed on a surface of theexposed region of the semiconductor material. The methods may alsoinclude forming a film of the halogen-containing precursor having apredetermined thickness on the surface of the exposed region of thesemiconductor material. The methods may further include pausing the flowof the halogen-containing precursor into the processing region of thesemiconductor processing chamber. The methods may also include etchingthe exposed region of the semiconductor material with the adsorbedhalogen-containing precursor. The adsorbed halogen-containing precursormay produce a fluoride of the semiconductor material. In someembodiments, the method may further include purging thehalogen-containing precursor not adsorbed on the surface of the exposedregion of the semiconductor material.

In some embodiments, the film of the halogen-containing precursor formedon the surface of the exposed region of the semiconductor material mayinclude an atomic layer of the halogen-containing precursor. In someembodiments, etching the exposed region of the semiconductor materialmay include isotropically etching the exposed region of thesemiconductor material. In some embodiments, the adsorbedhalogen-containing precursor may produce a noble gas. In someembodiments, the halogen-containing precursor may include at least oneof a noble gas compound precursor, an interhalogen precursor, or afluorinating precursor. In some embodiments, the semiconductor materialmay include at least one of silicon, germanium, or a compound thereof.In some embodiments, a temperature of the substrate may be maintained atabout room temperature. In some embodiments, the etching method may berepeated for at least two cycles. In some embodiments, a thickness ofthe semiconductor material etched during each cycle may be between about5 Å and about 50 Å. In some embodiments, the etching method may have aselectivity toward the semiconductor material to a metal-containingmaterial greater than or about 50:1. In some embodiments, themetal-containing material may include at least one of titanium, titaniumnitride, tantalum, tantalum nitride, tungsten, or titanium tungsten. Insome embodiments, a pressure within the semiconductor processing chambermay be maintained between about 5 mTorr and about 50 Torr.

The present technology may also include additional exemplary etchingmethods. The methods may include flowing a halogen-containing precursorinto a processing region of a semiconductor processing chamber. Themethods may further include contacting an exposed region of ametal-containing material with the halogen-containing precursor suchthat the halogen-containing precursor may be adsorbed on a surface ofthe exposed region of the metal-containing material. The methods mayfurther include forming a film of the halogen-containing precursor onthe surface of the exposed region of the metal-containing material. Themethods may also include pausing the flow of the halogen-containingprecursor into the processing region of the semiconductor processingchamber. The methods may further include etching the exposed region ofthe metal-containing material with the adsorbed halogen-containingprecursor. The adsorbed halogen-containing precursor may produce afluoride of the metal-containing material.

In some embodiments, the methods may further include purging thehalogen-containing precursor not adsorbed on the surface of the exposedregion of the metal-containing material such that an atomic layer of thehalogen-containing precursor may be produced on the surface of theexposed region of the metal-containing material. In some embodiments, atemperature of the substrate may be maintained between about roomtemperature and about 300° C. In some embodiments, the metal-containingmaterial may include at least one of molybdenum, titanium, titaniumnitride, tantalum, tantalum nitride, tungsten, or titanium tungsten. Insome embodiments, the halogen-containing precursor may include XeF₂.

In some embodiments, the methods may further include contacting anexposed region of a semiconductor material with the halogen-containingprecursor such that the halogen-containing precursor may be adsorbed ona surface of the exposed region of the semiconductor material. Themethods may further include forming a film of the halogen-containingprecursor on the surface of the exposed region of the semiconductormaterial. The methods may also include pausing the flow of thehalogen-containing precursor into the processing region of thesemiconductor processing chamber. The methods may further includeetching the exposed region of the semiconductor material with theadsorbed halogen-containing precursor on the surface of the exposedregion of the semiconductor material. The adsorbed halogen-containingprecursor may produce a fluoride of the semiconductor material.

The present technology may also include additional exemplary etchingmethods. The methods may include flowing a first halogen-containingprecursor into a processing region of a semiconductor processingchamber. The first halogen-containing precursor may include a noble gascompound precursor. The methods may further include contacting anexposed region of a semiconductor material with the firsthalogen-containing precursor such that the first halogen-containingprecursor may be adsorbed on a surface of the exposed region of thesemiconductor material. The methods may further include etching theexposed region of the semiconductor material with the adsorbed firsthalogen-containing precursor. The adsorbed first halogen-containingprecursor may produce a gaseous byproduct. The methods may also includeforming a second halogen-containing precursor from the gaseous byproductusing plasma.

In some embodiments, the methods may further include flowing the secondhalogen-containing precursor into the processing region of thesemiconductor processing chamber. The methods may also includecontacting the exposed region of the semiconductor material with thesecond halogen-containing precursor such that the secondhalogen-containing precursor may be adsorbed on the surface of theexposed region of the semiconductor material. In some embodiments, themethods may further include etching the exposed region of thesemiconductor material with the adsorbed second halogen-containingprecursor. The adsorbed second halogen-containing precursor may producea fluoride of the semiconductor material. In some embodiments, thegaseous byproduct may include at least one of a noble gas or a halogengas.

Such technology may provide numerous benefits over conventional systemsand techniques. For example, the technology may allow for highlyselective etching towards semiconductor materials over a wide variety ofmetals, oxides, nitrides, carbides, and/or organic compounds commonlyused in semiconductor processing. The technology may also allow forhighly selective etching of select metal-containing materials atelevated temperatures. The high selectivity offered by the technologymay further allow very thin mask materials to be used. Additionally, thetechnology may allow for very controlled delivery of precursors and mayachieve atomic or molecular layer etching of select semiconductor andmetal-containing materials to improve the uniformity of the etchedprofile. Further, the technology may allow for isotropic etching ofsemiconductor materials from all crystal planes. Moreover, thetechnology may be more economical by collecting and reusing select etchbyproducts. These and other embodiments, along with many of theiradvantages and features, are described in more detail in conjunctionwith the below description and attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a top plan view of one embodiment of an exemplaryprocessing system according to embodiments of the present technology.

FIG. 2A shows a schematic cross-sectional view of an exemplaryprocessing chamber according to embodiments of the present technology.

FIG. 2B shows a detailed view of a portion of the processing chamberillustrated in FIG. 2A according to embodiments of the presenttechnology.

FIG. 3 shows a bottom plan view of an exemplary showerhead according toembodiments of the present technology.

FIG. 4 shows exemplary operations in a method according to embodimentsof the present technology.

FIGS. 5A-5D show cross-sectional views of substrates being processedaccording to embodiments of the present technology.

FIG. 6 shows a schematic view of an exemplary precursor delivery systemaccording to embodiments of the present technology.

FIG. 7 shows exemplary operations in a method according to embodimentsof the present technology.

FIG. 8 shows exemplary operations in a method according to embodimentsof the present technology.

Several of the figures are included as schematics. It is to beunderstood that the figures are for illustrative purposes, and are notto be considered of scale unless specifically stated to be of scale.Additionally, as schematics, the figures are provided to aidcomprehension and may not include all aspects or information compared torealistic representations, and may include exaggerated material forillustrative purposes.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a letter thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the letter.

DETAILED DESCRIPTION

The selectivity of conventional wet chemistry etching processes foretching silicon relative to other materials is generally low. Inaddition, the wet chemistry etching processes can also becrystallographic, which means that etching of silicon may not be thesame at different cyrstal planes. For example, etching of silicon atsilicon crystal planes of (110), (111) or along the <110>, <111>direction may be so slow that the etching process may be substantiallystopped at these crystal planes or surfaces, which results in roughnessin the etched profile. Low selectivity toward silicon andcrystallographic etching are also common problems many dry etchingprocesses encounter.

The present technology overcomes these issues by utilizing one or morehalogen-containing persursors that may be highly selective towardssilicon over a wide variety of metals, oxides, nitrides, carbides,and/or organic compounds commonly used in semiconductor processing. Thehalogen-containing precursors may also allow for isotropic etching ofsemiconductor materials from all crystal planes. The technology furtherovercomes the issues associated with the conventional etching processesby controlling the delivery of the precursors to achieve atomic ormolecular layer etching and to obtain uniformity in the etched profile.Further, the present technology may be plasma free, which may limitdamage to the substrate features many conventional dry etching methodsmay cause. These and other embodiments, along with many of theiradvantages and features, are described in more detail in conjunctionwith the below description and attached figures.

Although the remaining disclosure will routinely identify specificetching processes utilizing the disclosed technology, it will be readilyunderstood that the systems and methods are equally applicable todeposition and cleaning processes as may occur in the describedchambers.

Accordingly, the technology should not be considered to be so limited asfor use with etching processes or chambers alone. Moreover, although anexemplary chamber is described to provide foundation for the presenttechnology, it is to be understood that the present technology can beapplied to virtually any semiconductor processing chamber that may allowthe single-chamber operations described.

FIG. 1 shows a top plan view of one embodiment of a processing system100 of deposition, etching, baking, and curing chambers according toembodiments. In the figure, a pair of front opening unified pods (FOUPs)102 supply substrates of a variety of sizes that are received by roboticarms 104 and placed into a low pressure holding area 106 before beingplaced into one of the substrate processing chambers 108 a-f, positionedin tandem sections 109 a-c. A second robotic arm 110 may be used totransport the substrate wafers from the holding area 106 to thesubstrate processing chambers 108 a-f and back. Each substrateprocessing chamber 108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation, and othersubstrate processes.

The substrate processing chambers 108 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricor metallic film on the substrate wafer. In one configuration, two pairsof the processing chambers, e.g., 108 c-d and 108 e-f, may be used todeposit material on the substrate, and the third pair of processingchambers, e.g., 108 a-b, may be used to etch the deposited material. Inanother configuration, all three pairs of chambers, e.g., 108 a-f, maybe configured to etch a dielectric or metallic film on the substrate.Any one or more of the processes described may be carried out inchamber(s) separated from the fabrication system shown in differentembodiments. It will be appreciated that additional configurations ofdeposition, etching, annealing, and curing chambers for dielectric filmsare contemplated by system 100.

FIG. 2A shows a cross-sectional view of an exemplary process chambersystem 200 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., titanium nitride,tantalum nitride, tungsten, copper, cobalt, silicon, polysilicon,silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide,etc., a process gas may be flowed into the first plasma region 215through a gas inlet assembly 205. A remote plasma system (RPS) 201 mayoptionally be included in the system, and may process a first gas whichthen travels through gas inlet assembly 205. The inlet assembly 205 mayinclude two or more distinct gas supply channels where the secondchannel (not shown) may bypass the RPS 201, if included.

A cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225,and a substrate support 265, having a substrate 255 disposed thereon,are shown and may each be included according to embodiments. Thepedestal 265 may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate, whichmay be operated to heat and/or cool the substrate or wafer duringprocessing operations. The wafer support platter of the pedestal 265,which may comprise aluminum, ceramic, or a combination thereof, may alsobe resistively heated in order to achieve relatively high temperatures,such as from up to or about 100° C. to above or about 600° C., using anembedded resistive heater element.

The faceplate 217 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 217 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 201, may pass through a plurality of holes, shown in FIG. 2B, infaceplate 217 for a more uniform delivery into the first plasma region215.

Exemplary configurations may include having the gas inlet assembly 205open into a gas supply region 258 partitioned from the first plasmaregion 215 by faceplate 217 so that the gases/species flow through theholes in the faceplate 217 into the first plasma region 215. Structuraland operational features may be selected to prevent significant backflowof plasma from the first plasma region 215 back into the supply region258, gas inlet assembly 205, and fluid supply system 210. The faceplate217, or a conductive top portion of the chamber, and showerhead 225 areshown with an insulating ring 220 located between the features, whichallows an AC potential to be applied to the faceplate 217 relative toshowerhead 225 and/or ion suppressor 223. The insulating ring 220 may bepositioned between the faceplate 217 and the showerhead 225 and/or ionsuppressor 223 enabling a capacitively coupled plasma (CCP) to be formedin the first plasma region. A baffle (not shown) may additionally belocated in the first plasma region 215, or otherwise coupled with gasinlet assembly 205, to affect the flow of fluid into the region throughgas inlet assembly 205.

The ion suppressor 223 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of ionically-charged species out ofthe first plasma region 215 while allowing uncharged neutral or radicalspecies to pass through the ion suppressor 223 into an activated gasdelivery region between the suppressor and the showerhead. Inembodiments, the ion suppressor 223 may comprise a perforated plate witha variety of aperture configurations. These uncharged species mayinclude highly reactive species that are transported with less reactivecarrier gas through the apertures.

As noted above, the migration of ionic species through the holes may bereduced, and in some instances completely suppressed. Controlling theamount of ionic species passing through the ion suppressor 223 mayadvantageously provide increased control over the gas mixture broughtinto contact with the underlying wafer substrate, which in turn mayincrease control of the deposition and/or etch characteristics of thegas mixture. For example, adjustments in the ion concentration of thegas mixture can significantly alter its etch selectivity, e.g.,SiNx:SiOx etch ratios, Si:SiOx etch ratios, etc. In alternativeembodiments in which deposition is performed, it can also shift thebalance of conformal-to-flowable style depositions for dielectricmaterials.

The plurality of apertures in the ion suppressor 223 may be configuredto control the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 223. For example, theaspect ratio of the holes, or the hole diameter to length, and/or thegeometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 223 is reduced. The holes in the ion suppressor 223 mayinclude a tapered portion that faces the plasma excitation region 215,and a cylindrical portion that faces the showerhead 225. The cylindricalportion may be shaped and dimensioned to control the flow of ionicspecies passing to the showerhead 225. An adjustable electrical bias mayalso be applied to the ion suppressor 223 as an additional means tocontrol the flow of ionic species through the suppressor.

The ion suppressor 223 may function to reduce or eliminate the amount ofionically charged species traveling from the plasma generation region tothe substrate. Uncharged neutral and radical species may still passthrough the openings in the ion suppressor to react with the substrate.It should be noted that the complete elimination of ionically chargedspecies in the reaction region surrounding the substrate may not beperformed in embodiments. In certain instances, ionic species areintended to reach the substrate in order to perform the etch and/ordeposition process. In these instances, the ion suppressor may help tocontrol the concentration of ionic species in the reaction region at alevel that assists the process.

Showerhead 225 in combination with ion suppressor 223 may allow a plasmapresent in first plasma region 215 to avoid directly exciting gases insubstrate processing region 233, while still allowing excited species totravel from chamber plasma region 215 into substrate processing region233. In this way, the chamber may be configured to prevent the plasmafrom contacting a substrate 255 being etched. This may advantageouslyprotect a variety of intricate structures and films patterned on thesubstrate, which may be damaged, dislocated, or otherwise warped ifdirectly contacted by a generated plasma. Additionally, when plasma isallowed to contact the substrate or approach the substrate level, therate at which oxide species etch may increase. Accordingly, if anexposed region of material is oxide, this material may be furtherprotected by maintaining the plasma remotely from the substrate.

The processing system may further include a power supply 240electrically coupled with the processing chamber to provide electricpower to the faceplate 217, ion suppressor 223, showerhead 225, and/orpedestal 265 to generate a plasma in the first plasma region 215 orprocessing region 233. The power supply may be configured to deliver anadjustable amount of power to the chamber depending on the processperformed. Such a configuration may allow for a tunable plasma to beused in the processes being performed. Unlike a remote plasma unit,which is often presented with on or off functionality, a tunable plasmamay be configured to deliver a specific amount of power to the plasmaregion 215. This in turn may allow development of particular plasmacharacteristics such that precursors may be dissociated in specific waysto enhance the etching profiles produced by these precursors.

A plasma may be ignited either in chamber plasma region 215 aboveshowerhead 225 or substrate processing region 233 below showerhead 225.Plasma may be present in chamber plasma region 215 to produce theradical precursors from an inflow of, for example, a fluorine-containingprecursor or other precursor. An AC voltage typically in the radiofrequency (RF) range may be applied between the conductive top portionof the processing chamber, such as faceplate 217, and showerhead 225and/or ion suppressor 223 to ignite a plasma in chamber plasma region215 during deposition. An RF power supply may generate a high RFfrequency of 13.56 MHz but may also generate other frequencies alone orin combination with the 13.56 MHz frequency.

FIG. 2B shows a detailed view 253 of the features affecting theprocessing gas distribution through faceplate 217. As shown in FIGS. 2Aand 2B, faceplate 217, cooling plate 203, and gas inlet assembly 205intersect to define a gas supply region 258 into which process gases maybe delivered from gas inlet 205. The gases may fill the gas supplyregion 258 and flow to first plasma region 215 through apertures 259 infaceplate 217. The apertures 259 may be configured to direct flow in asubstantially unidirectional manner such that process gases may flowinto processing region 233, but may be partially or fully prevented frombackflow into the gas supply region 258 after traversing the faceplate217.

The gas distribution assemblies such as showerhead 225 for use in theprocessing chamber section 200 may be referred to as dual channelshowerheads (DCSH) and are additionally detailed in the embodimentsdescribed in FIG. 3. The dual channel showerhead may provide for etchingprocesses that allow for separation of etchants outside of theprocessing region 233 to provide limited interaction with chambercomponents and each other prior to being delivered into the processingregion.

The showerhead 225 may comprise an upper plate 214 and a lower plate216. The plates may be coupled with one another to define a volume 218between the plates. The coupling of the plates may be so as to providefirst fluid channels 219 through the upper and lower plates, and secondfluid channels 221 through the lower plate 216. The formed channels maybe configured to provide fluid access from the volume 218 through thelower plate 216 via second fluid channels 221 alone, and the first fluidchannels 219 may be fluidly isolated from the volume 218 between theplates and the second fluid channels 221. The volume 218 may be fluidlyaccessible through a side of the gas distribution assembly 225.

FIG. 3 is a bottom view of a showerhead 325 for use with a processingchamber according to embodiments. Showerhead 325 may correspond with theshowerhead 225 shown in

FIG. 2A. Through-holes 365, which show a view of first fluid channels219, may have a plurality of shapes and configurations in order tocontrol and affect the flow of precursors through the showerhead 225.Small holes 375, which show a view of second fluid channels 221, may bedistributed substantially evenly over the surface of the showerhead,even amongst the through-holes 365, and may help to provide more evenmixing of the precursors as they exit the showerhead than otherconfigurations.

The chambers discussed previously may be used in performing exemplarymethods including etching methods. Turning to FIG. 4 is shown exemplaryoperations in a method 400 according to embodiments of the presenttechnology. Prior to the first operation of the method, a substrate maybe processed in one or more ways before being placed within a processingregion of a chamber in which method 400 may be performed. For example,films or layers may be deposited, grown, or otherwise formed on thesubstrates, and masks for patterning the films or layers may be formedto produce features. Vias, trenches, and/or lateral recesses may beformed or defined within the substrate. The vias or trenches may have anaspect ratio, or a ratio of their height to width, greater than or about2, greater than or about 5, greater than or about 10, greater than orabout 20, greater than or about 30, greater than or about 50, or more inembodiments. Similarly, the lateral recesses may have an aspect ratio,or a ratio of their depth extending laterally to their height expandingvertically, greater than or about 2, greater than or about 5, greaterthan or about 10, greater than or about 20, greater than or about 30,greater than or about 50, or more in embodiments. In some embodiments, aliner material may be formed along the trench or recess sidewalls toprotect the substrate from metal diffusion.

The operations of method 400 will now be described in conjunction withthe schematic illustration of FIGS. 5A-5D. FIG. 5A illustrates a portionof a processed structure 500 a. The processed structure 500 a may beproduced during a multi-patterning process. The processed structure 500a may be further developed in producing, for example, FinFET structures,or any other semiconductor structures. The processed structure 500 a mayinclude layered materials and features overlaying a substrate 505. Forexample, the processed structure may include a patterned structure 510sandwiched between adjacent hard mask spacers 515. Although only onepatterned structure 510 and two adjacent hard spacers 515 are shown inFIG. 5A, the processed structure 500 a may include more than onepatterned structure 510 each of which may be sandwiched between two hardmask spacers 515. The patterned structure 510 may include asemiconductor material, such as silicon, germanium, silicon germanium,or may include a metal or metal-containing material, such as molybdenum.The hard mask spacer 515 may include a nitride, such as silicon nitride,a carbide, such as silicon carbide, an oxide, such as a thermal oxide orlow temperature oxide which may include silicon oxide or other oxidethat may be used or useful in semiconductor processes.

The patterned structure 510 may further include one or more layeredmaterials above which the patterned structure 510 and the hard maskspacer 515 may be formed. The processed structure 500 a may include afirst layer 520 above which the patterned structure 510 and the hardmask spacer 515 may be formed. The first layer 520 may include anotherhard mask material, which may be the same as or different from thematerial of the hard mask spacers 515. The first layer 520 may include anitride, such as silicon nitride, a carbide, such as silicon carbide, anoxide, such as a thermal oxide or low temperature oxide which mayinclude silicon oxide or other oxide, and so on. The processed structure500 a may further include a second layer 525 below the first layer 520and above the substrate 505. The second layer 525 may include anothersemiconductor material, which may be the same as or different from thematerial of the patterned structure 510. The second layer 525 mayinclude silicon, germanium, silicon germanium, or molybdenum. In someembodiments, the first layer 520 may be formed by performing anoxidation process on the second layer 525. Accordingly, the first layer520 may include an oxide layer of the material of the second layer 525.For example, the second layer 525 may include silicon, and the firstlayer 520 may include silicon oxide. Although the first layer 520 andthe second layer 525 are described herein as examples, the processedstructure 500 a may include only one or more than two layers between thepatterned structure 510 and the substrate 505.

In some embodiments, the processed structure 500 a may be produced inthe same processing chamber as the processing chamber in which method400 may be performed, or may be produced in a different processingchamber and then transferred to the processing chamber in which method400 may be performed. Once the substrate 505 may be positioned within aprocessing region of a semiconductor processing chamber, such as thesubstrate processing region 233 of the processing chamber 200 discussedabove with reference to FIG. 2A, method 400 may be initiated by flowinga halogen-containing precursor into the processing region at operation405. Method 400 may further include, at operation 410, contactingexposed regions of the processed structure 500 a, which may includeexposed regions of the semiconductor materials forming the patternedstructure 510 and exposed regions of nitride, carbide, or oxide formingthe hard mask spacers 515 and the first layer 520, with thehalogen-containing precursor. During this operation, thehalogen-containing precursor may be adsorbed at the surfaces of theexposed regions of the processed structure 500 a. Method 400 may furtherinclude forming a film of the halogen-containing precursor at theexposed regions of the processed structure 500 a at operation 415. Aswill be described in more detail below, the thickness of thehalogen-containing precursor film formed at the exposed surfaces of theprocessed structure 500 a may be controlled such that a predeterminedthickness, including an atomic layer, a molecular layer, a few atomiclayers, or a few molecular layers in some embodiments, of thehalogen-containing precursor film may be obtained, which in turn maylead to controlled etching, such as atomic layer etching or molecularlayer etching, of the exposed regions of the processed structure 500 a.

The halogen-containing precursor may include a variety of fluids, andmay include one or more of noble gas compound precursors, interhalogenprecursors, fluorinating precursors, or other halogen-containingprecursors that may be used or useful in semiconductor processes. Thenoble gas compound precursors may include one or more noble gas halides,which may include xenon halides, such as xenon fluoride, kryptonhalides, such as krypton fluoride, or any other compounds including anoble gas element and a halogen that may be used or useful insemiconductor processes.

One exemplary noble gas compound precursor may include xenon difluoride(XeF₂). Xenon difluoride may include a vapor pressure of about 4 Torr atabout 25° C. As mentioned above, the halogen-containing precursor filmformed on the exposed surfaces of the processed structure 500 a may beformed to a predetermined thickness, and in some embodiments, the filmformed may include an atomic layer, a molecular layer, a few atomiclayers, or a few molecular layers of the halogen-containing precursor.To achieve such predetermined thickness, xenon difluoride vapor or gasmay be formed in a loading chamber before being flowed into theprocessing region of the processing chamber where the processedstructure 500 a may be positioned. To vaporize xenon difluoride, thepressure of the loading chamber may be maintained at about 4 Torr, andthe temperature of the loading chamber may be maintained at about 25° C.The pressure and/or temperature of the loading chamber may be maintainedat other suitable ranges, although the pressure may be maintained withina relatively low range to facilitate controlled flow of the xenondifluoride vapor or gas into the processing chamber where the processedstructure 500 a may be positioned, and the temperature may be maintainedto be similar to the temperature at which method 400 may be performed.

For example, the pressure of the loading chamber may be maintained belowor about 20 Torr in embodiments. The pressure of the loading chamber maybe maintained below or about 15 Torr, and may be maintained below orabout 10 Torr, below or about 5 Torr, below or about 4 Torr, below orabout 3 Torr, below or about 2 Torr, below or about 1 Torr, below orabout 500 mTorr, below or about 100 mTorr, below or about 50 mTorr,below or about 20 mTorr, below or about 10 mTorr, below or about 5mTorr, below or about 4 mTorr, below or about 3 mTorr, below or about 2mTorr, below or about 1 mTorr, or lower. In embodiments the pressure maybe maintained between about 500 mTorr and about 10 Torr. In embodimentsthe pressure may be maintained below about 500 mTorr. The temperature ofthe loading chamber may be maintained between about 0° C. and about 50°C. in embodiments. The temperature may be maintained above or about 5°C., and may be maintained above or about 10° C., above or about 15° C.,above or about 20° C., above or about 25° C., above or about 30° C.,above or about 35° C., above or bout 40° C., above or about 45° C.,above or about 50° C., or higher. When xenon difluoride gas may not beincluded or flowed into the processing chamber, the pressure of theloading chamber may be maintained at an increased level, and/or thetemperature of the loading chamber may be maintained at a decreasedlevel such that xenon difluoride may be preserved in the loading chamberin a solid form.

Once vaporized in the loading chamber, the xenon difluoride vapor or gasmay then be flowed into the processing region of the processing chamberwhere the processed structure 500 a may be positioned via a gasdistribution assembly of the processing chamber, such as the gasdistribution assembly 205 of the processing chamber 200 described abovewith reference to FIG. 2 at operation 405. The xenon difluoride gas mayalso be flowed through one or more faceplates and/or showerheads, suchas the faceplate 217 and the showerhead 225 described above withreference to FIG. 2, to facilitate even distribution of the precursoronto the processed structure 500 a. At operation 410, the xenondifluoride gas may then contact the exposed regions of the processedstructure 500 a, and may form a film on the exposed surfaces of theprocessed structure 500 a at operation 415. Although a loading chamberis described herein as an example for delivery of xenon difluoride,xenon difluoride, as well as other halogen-containing precursors, may begenerated in situ in some embodiments of the technology, as will bedescribed in more detail below.

The interhalogen precursors may include one or more compounds containingtwo or more halogen elements, such as one or more fluorides containingfluorine and one or more of chlorine, bromine, or iodine, one or morechlorides containing chlorine and one or more of fluorine, bromine, oriodine, one or more bromides containing bromine and one or more offluorine, chlorine, or iodine, or other interhalogen precursors that maybe used or useful in semiconductor processes. Some exemplaryinterhalogen precursors may include iodine fluoride, such as iodinemonofluoride, iodine trifluoride, iodine pentafluoride, iodineheptafluoride, and may further include chlorine fluoride, such aschlorine monofluoride, chlorine trifluoride, chlorine pentafluoride, andso on. As compared to diatomic halogens, interhalogen compounds may bemore reactive and thus serve better halogenating agents because theinterhalogen bonds may be weaker as compared to diatomic halogen bonds,except for F₂. The highly reactive interhalogen compounds may be used ashalogen-containing precursors for selective etching of semiconductor orother materials used in semiconductor processes and devicemanufacturing. During the etching process, the element of theinterhalogen having a relatively higher electronegativity, such asfluorine, may react with the materials to be etched to form volatileetching byproducts, and the element of the interhalogen having arelatively lower electronegativity may be recycled to re-form one ormore halogen-containing precursors using a plasma process, as will bedescribed in more detail below.

The fluorinating precursors may include any of the noble gas compoundprecursors or the interhalogen precursors described above, or otherfluorinating precursors that may be used or useful in selective etchingof semiconductor or other materials used in semiconductor processes anddevice manufacturing.

To achieve the predetermined thickness, such an atomic layer, amolecular layer, a few atomic layers, or a few molecular layers, of thexenon difluoride film or other halogen-containing precursor film formedon the exposed surfaces of the processed structure 500 a, the amount ordosage of xenon difluoride or other halogen-containing precursorsdelivered to the processing region of the processing chamber where theprocessed structure 500 a may be positioned may be controlled. Forexample, the amount or dosage of the xenon difluoride gas or otherhalogen-containing precursors that may be flowed into the processingregion may be predetermined or calculated based on desired filmthickness, the flow rate at which xenon difluoride or otherhalogen-containing precursors may be flowed, the amount of time duringwhich xenon difluoride or other halogen-containing precursors may beflowed, the pressure of the processing region, the temperature of theprocessing region and/or the processed structure 500 a, the particularstructures and features of the processed structure 500 a, and so on.

In some embodiments, a precursor delivery system incorporating one ormore precision valves may be utilized to facilitate the controlleddelivery of the halogen-containing precursors. With reference to FIG. 6,an exemplary precursor delivery system 600 may include a loading chamber602, such as the loading chamber discussed above for forming vaporizedxenon difluoride precursor. In some embodiments, the loading chamber 602may also be configured to contain any other halogen-containingprecursors described herein. In some embodiments, the loading chamber602 may include or may employ a bubbler for facilitating delivery ofxenon difluoride or other halogen-containing precursors. To control theamount or dosage of the halogen-containing precursors flowed from theloading chamber 602 to the processing chamber 604 within which theprocessed structure 500 a may be positioned, and which may berepresentative of any of the previously described chambers, a precisionvalve 606 may be coupled to an outlet line of the loading chamber 602.In some embodiments, the precision valve 606 may include one or moreatomic layer deposition valves. The atomic layer deposition valves mayinclude high-speed pneumatic valves. The high-speed pneumatic valves maybe opened for a period of time that may be less than or about a fewseconds in embodiments, and may be opened for less than or about 1second, less than or about 0.5 seconds, less than or about 0.1 seconds,less than or about 50 milliseconds, less than or about 40 milliseconds,less than or about 30 milliseconds, less than or about 20 milliseconds,less than or about 10 milliseconds, less than or about 5 milliseconds,less than or about 4 milliseconds, less than or about 3 milliseconds,less than or about 2 milliseconds, less than or about 1 millisecond, orless. In some embodiments, before being flowed into the processingchamber 604, the halogen-containing precursors may be mixed or combinedwith one or more carrier gases. For example, when the precision valve606 may be opened, the halogen-containing precursors may be flowed intoa carrier gas line 608. Through the carrier gas line 608, the carriergases may be flowed and may carry the halogen-containing precursors tothe processing chamber 604. The flow of the carrier gases may becontrolled through one or more mass-flow controllers 612.

The flow rate and/or amount of the halogen-containing precursors flowedinto the processing chamber 604 may be controlled in a variety of ways.In some embodiments, the precision valve 606 may be opened for apredetermined period of time to control the halogen-containingprecursors flowed into the carrier gas line 608. For example, theprecision valve 606 may be opened for a period of time less than orabout 1 second, less than or about 0.5 seconds, less than or about 0.1seconds, less than or about 50 milliseconds, less than or about 40milliseconds, less than or about 30 milliseconds, less than or about 20milliseconds, less than or bout 10 milliseconds, less than or about 5milliseconds, less than or about 4 milliseconds, less than or about 3milliseconds, less than or about 2 milliseconds, less than or about 1millisecond, or less, depending on the specific application or processmay require. In some embodiments, the flow rate and/or amount of thehalogen-containing precursors flowed into the processing chamber 604 mayalso be controlled by adjusting the flow of the carrier gases to obtaina desired dilution factor. In some embodiments, a ratio of the flow rateof the carrier gases to the flow rate of the halogen-containingprecursors before combining may be greater than or about 5:1, greaterthan or about 10:1, greater than or about 20:1, greater than or about50:1, greater than or about 100:1, greater than or about 200:1, greaterthan or about 300:1, greater than or about 400:1, greater than or about500:1, or more. By controlling the period of time the precision valve606 may be opened and/or the dilution of the halogen-containingprecursors by the carrier gases, the amount or dosage of thehalogen-containing precursors delivered to the processing chamber 604may be controlled to obtain desired etching rates.

Depending on the specific applications, in some embodiments, the flowrate of xenon difluoride or other halogen-containing precursors may beless than or about 50 sccm in embodiments, and may be less than or about45 sccm, less than or about 40 sccm, less than or bout 35 sccm, lessthan or about 30 sccm, less than or about 25 sccm, less than or about 20sccm, less than or about 15 sccm, less than or about 10 sccm, less thanor about 5 sccm, less than or about 3 sccm, less than or about 1 sccm,or less. The flow rate of the xenon difluoride gas or otherhalogen-containing precursors may be maintained at a relatively lowlevel to facilitate dosage control as well as to improve the uniformityof the thickness of the film formed at the exposed surfaces of theprocessed structure 500 a.

Additionally, the flow or delivery of xenon difluoride or otherhalogen-containing precursors may be pulsed for time periods of lessthan or about 30 seconds in embodiments, and may be pulsed for timeperiods of less than or about 25 seconds, less than or about 20 seconds,less than or about 15 seconds, less than or about 10 seconds, less thanor about 5 seconds, less than or about 2 seconds, or less. Between eachof the pulsed flow or delivery, the flow or delivery of xenon difluorideor other halogen-containing precursors may be paused for less than orabout 30 seconds in embodiments, and may be paused for time periods ofless than or about 25 seconds, less than or about 20 seconds, less thanor about 15 seconds, less than or about 10 seconds, less than or about 5seconds, less than or about 2 seconds, or less. Additionally, the flowrate and pulsing may be combined for any of the listed numbers. Forexample, the flow rate of xenon difluoride or other halogen-containingprecursors may be below or about 10 sccm and may be delivered in pulsesfrom about 5 to about 10 seconds in embodiments, depending on thedesired thickness of the film formed.

In some embodiments, the pressure of the processing region may bemaintained below or about 50 Torr in embodiments. The pressure may bemaintained below or about 40 Torr, and may be maintained below or about30 Torr, below or about 20 Torr, below or about 15 Torr, below or about10 Torr, below or about 5 Torrr, below or about 4 Torr, below or about 3Torr, below or about 2 Torr, below or about 1 Torr, below or about 800mTorr, below or about 600 mTorr, below or about 400 mTorr, below orabout 200 mTorr, below or about 100 mTorr, below or about 80 mTorr,below or about 60 mTorr, below or about 40 mTorr, below or about 20mTorr, below or about 10 mTorr, below or about 5 mTorr, below or about 2mTorr, below or bout 1 mTorr, or lower. Maintaining a relatively lowpressure inside the processing chamber may facilitate even adsorptionand uniform film formation by the halogen-containing precursors at thesurfaces of the processed structure 500 a, and in some embodiments, tofacilitate atomic or molecular layer adsorption of xenon difluoride orother halogen-containing precursors at the exposed surfaces.

In some embodiments, the temperature of the processing region or at thesubstrate level may be maintained between about 0° C. and about 100° C.in embodiments. The temperature may be maintained above or about 5° C.,and may be maintained above or about 10° C., above or about 15° C.,above or about 20° C., above or about 25° C., above or about 30° C.,above or about 35° C., above or about 40° C., above or about 45° C.,above or about 50° C., above or about 60° C., above or about 70° C.,above or about 80° C., above or about 90° C., or higher. In someembodiments, the temperature of the processing region or at thesubstrate level may be maintained at about room temperature or thechamber temperature without additional heating or cooling performed atthe substrate level. The room temperature may range between about 10° C.and about 50° C.

By controlling the flow of the halogen-containing precursors, thetemperature and/or pressure of the loading chamber of thehalogen-containing precursors (if utilized), the temperature and/orpressure of the processing region of the chamber where the processedstructure 500 a may be positioned, and/or other operational parameters,a film of the halogen-containing precursors with a desired thickness,including atomic-layer thickness, and uniformity may be formed at theexposed regions of the processed structure 500 a. As mentioned above,controlled film formation of the halogen-containing precursors at theexposed regions of the processed structure 500 a may further lead tocontrolled etching, including atomic or molecular layer etching in someembodiments, of the exposed regions of the processed structure 500 a. Insome embodiments, method 400 may also include pausing the flow of thehalogen-containing precursors at operation 420 by halting the flow ofthe halogen-containing precursors, and may further include purging thehalogen-containing precursors that may not be adsorbed on the exposedsurfaces of the processed structure 500 a at operation 425 using one ormore inert gases. In some embodiments, the purging operation 425 may beperformed immediately after the predetermined amount of thehalogen-containing precursors may be flowed. In some embodiments, thepurging operation 425 may be performed after the flow of thehalogen-containing precursors may be paused for a period of time so asto allow the halogen-containing precursors to flow onto and to beadsorbed on the exposed surfaces of the processed structure 500 a. Forexample, the purging operation 425 may be performed after the flow ofthe halogen-containing precursors may be paused for a time period ofless than or about 30 seconds in embodiments, and may be paused for timeperiods of less than or about 25 seconds, less than or bout 20 seconds,less than or about 15 seconds, less than or about 10 seconds, less thanor about 5 seconds, less than or about 2 seconds, or less.

By performing these operations 420, 425, only the halogen-containingprecursors that may be adsorbed at the exposed surfaces of the processedstructure 500 a may remain in the processing region forming thehalogen-containing precursor film of the predetermined thickness, andany excess may be removed from the processing region. Method 400 maythen proceed to operation 430 to etch the exposed regions of theprocessed structure 500 a with the adsorbed halogen-containingprecursors. Because the thickness of the halogen-containing precursorfilm may be predetermined, or in other words, the amount of thehalogen-containing precursors available for the etching operation 430may be predetermined, the thickness or amount of the materials etchedmay be controlled at operation 430. In some embodiments, when one or afew atomic or molecular layers of the halogen-containing precursors maybe adsorbed at the exposed surfaces of the processed structure 500 aafter performing operations 405-425, atomic or molecular layer etchingof select materials (discussed further below) at the exposed regions ofthe processed structure 500 a may be achieved in operation 430.

In some embodiments, depending on the thickness or amount of thehalogen-containing precursors adsorbed, a thickness of less than orabout 5 nm of select materials at the exposed regions of the processedstructure 500 a may be etched or removed. In some embodiments, anetching or removal thickness of less than or about 4 nm, less than orabout 3 nm, less than or bout 2 nm, less than or about 1 nm, less thanor about 9 Å, less than or about 8 Å, less than or bout 7 Å, less thanor about 6 Å, less than or about 5 Å, less than or about 4 Å, less thanor bout 3 Å, less than or about 2 Å, or less in embodiments. In someembodiments, the removal may be at least about 5 Å, and may be betweenabout 5 Å and about 5 nm of removal, or between about 10 Å and about 2nm of removal. In some embodiments, method 400 may be repeated forseveral cycles to achieve a greater overall removal thickness. In someembodiments, method 400 may be repeated for at least two cycles, and maybe repeated for at least about 3 cycles, at least about 5 cycles, atleast about 8 cycles, at least about 10 cycles, at least about 20cycles, at least about 50 cycles, at least about 100 cycles, or more.The number of cycles may be dependent on the amount of removal providedby each cycle. By performing method 400 in cycles and removing only acontrolled amount, including in some embodiments, one or a few atomic ormolecular layers, of the materials to be etched, a uniform or smoothetching profile may be obtained.

As mentioned previously, not all exposed regions of the processedstructure 500 a may be etched by the halogen-containing precursors, andonly select materials may be etched, depending on the operationalparameters of the processing region and the materials at the exposedregions of the processed structure 500 a. In the example as shown inFIG. 5A, during operation 430, the halogen-containing precursors mayinteract with the patterned structure 510, which may include one or moresemiconductor materials, such as silicon, germanium, silicon germanium,or may include a metal or metal-containing, such as molybdenum. Theremay be substantially no or very limited interaction between thehalogen-containing precursors and the hard mask spacers 515 or the firstlayer 520, which may include one or more of a nitride, a carbide, or anoxide, such as silicon nitride, silicon carbide, or silicon oxide. Atabout room temperature, the halogen-containing precursors may have aselectivity toward the semiconductor material forming the patternedstructure 510 to the nitride, carbide, or oxide material forming thehard mask spacers 515 or the first layer 520 greater than or about100:1, greater than or about 200:1, greater than or about 300:1, greaterthan or about 400:1, or higher depending on the operating conditions.

The interaction between the adsorbed halogen-containing precursors withthe exposed semiconductor material of the patterned structure 510 mayproduce one or more volatile substances, which may then be removed fromthe processing chamber. The volatile byproducts produced by theinteraction between the halogen-containing precursors and thesemiconductor material may include a halide of the semiconductormaterial, such as a fluoride of the semiconductor material, which mayinclude silicon fluoride, such as silicon tetrafluoride, germaniumfluoride, such as germanium tetrafluoride, molybdenum fluoride, such asmolybdenum hexafluoride, or any fluorinated compound or molecule of theetched material. The volatile byproducts produced may further include anoble gas or a halogen, depending on the halogen-containing precursorsflowed. For example, when a noble gas halide, such as xenon difluoride,may be used as one of the halogen-containing precursors, xenon gas maybe released and may be removed from the chamber. When an interhalogen,such as chlorine fluoride, may be used as one of the halogen-containingprecursors, chlorine gas may be released and may be removed from thechamber. As will be described in more detail below, the noble gas orhalogen released may be captured and recycled to produce additionalhalogen-containing precursors.

Although not shown in FIG. 5A, the processed structure 500 a may furtherinclude exposed regions of one or more metal-containing materials. Insome embodiments, the metal-containing materials may include titanium,tantalum, tungsten, or one or more compounds thereof, such as titaniumnitride, tantalum nitride, titanium tungsten, and so on. Thehalogen-containing precursors substantially may not interact with or mayinteract only to a limited extent with these metal-containing materialsat about room temperature, although the halogen-containing precursorsmay interact and thus etch these metal-containing materials at elevatedtemperatures as will be discussed in more detail below. At about roomtemperature, the halogen-containing precursors may have a selectivitytowards the semiconductor material forming the patterned structure 510over titanium, titanium nitride, tantalum, tantalum nitride, tungsten,or titanium tungsten of greater than or about 50:1, greater than orabout 100:1, greater than or about 150:1, greater than or about 200:1,or higher depending on the operating conditions.

In some embodiments, the processed structure 500 a may further includeexposed regions of other metal-containing materials that thehalogen-containing precursors substantially may not interact with or mayonly react to a limited extent at room or elevated temperatures. Suchmetal-containing materials may include gold, copper, aluminum, nickel,chrome, platinum, gallium, hafnium, and so on. In some embodiments, thehalogen-containing precursors, such as xenon difluoride, may notinteract with aluminum, nickel, chrome, platinum, gallium, hafnium orthe interaction with these metals may be so limited that the selectivitytoward the semiconductor material forming the patterned structure 510 tothese metals may be close to infinite.

Other commonly used materials in semiconductor processing that thehalogen-containing precursors may not interact with may further includealuminum nitride, gallium arsenide, select oxides, such as PZT,magnesium oxide, zinc oxide, hafnium oxide, titanium oxide, aluminumoxide, zirconium dioxide, and so on. The halogen-containing precursorsmay not interact with polymers or select organic compounds commonly usedin semiconductor processing, such as photoresists, PDMS(polydimethylsiloxane), C₄F₈, silica glass, dicing tape, PP(polypropylene), PEN (polyethylene naphthalate), PET (polyethyleneterephthalate), ETFE (ethylene tetrafluoroethylene), acrylic, and so on.

Because the halogen-containing precursors may have a high selectivitytoward the semiconductor material forming the patterned structure 510over the materials forming the hard mask spacers 515 and the first layer520 as discussed above, by performing method 400 in one or more cycles,the processed structure 500 a as shown in FIG. 5A may be developed intothe processed structure 500 b shown in FIG. 5B. In some embodiments, theprocessed structure 500 b may be further processed into the processedstructure 500 c shown in FIG. 5C, with only the portions of the firstlayer 520 below the hard mask spacers 515 remaining, the hard maskspacers 515 and the portions of the first layer 520 not covered by thehard mask spacers 515 being removed. The processed structure 500 c maybe produced using deposition of mask layers combined with dry etchingprocesses, which may be performed in the same processing chamber asmethod 400.

Once the processed structure 500 c may be produced, method 400 may beinitiated again or repeated to further develop the processed structure500 c into the processed structure 500 d shown in FIG. 5D. Specifically,as discussed above, the first layer 520 may include a nitride, such assilicon nitride, a carbide, such as silicon carbide, an oxide, such as athermal oxide or low temperature oxide which may include silicon oxideor other oxide, and so on, and the second layer 525 may include asemiconductor material, such as silicon, germanium, silicon germanium,or may include a metal or metal-containing material, such as molybdenum.As also discussed above, the halogen-containing precursors may have ahigh selectivity towards semiconductor materials, such as those includedin the second layer 525 over the nitride, carbide, or oxide which may beincluded in the first layer 520. Therefore, when one or morehalogen-containing precursors may be flowed into the processing region,the second layer 525 may be etched or removed by the halogen-containingprecursors while the remaining portions of the first layer 520 may notbe removed, and the processed structure 500 d of FIG. 5D may beproduced. The processed structure 500 d may be produced by performingmethod 400 for one or more cycles, with each cycle removing apredetermined thickness of the second layer 525 material, and in someembodiments, with each cycle removing only one or a few atomic ormolecular layers of the second layer 525 material.

There are several advantages of method 400. Because thehalogen-containing precursors used in method 400 may have very highselectivity towards semiconductor materials over a wide variety ofmetals, oxide, nitride, or carbide commonly used in semiconductorprocessing, method 400 may be used for selective etching ofsemiconductor materials, such as silicon, germanium, silicon germanium,or may be used for selective etching of metal or metal-containingmaterials, such as molybdenum, using very thin mask materials. Forexample, as shown in FIGS. 5A and 5B, selective etching of thesemiconductor material forming the patterned structure 510 may beachieved using very narrow masks or spacers, such as the hard maskspacers 515, which may be only a few nanometers or less. Similarly, asshown in FIGS. 5C and 5D, selective etching of the semiconductormaterial forming the second layer 525 may also be achieved using verythin masks, such as the first layer 520, which may be only a fewnanometers, a few angstroms, or less. Additionally, by controlling thethickness of the halogen-containing precursors adsorbed on exposedregions of materials to be etched and by performing method 400 incycles, atomic or molecular layer etching in each cycle may be achieved,and the uniformity of the etched profile may also be improved. Moreover,as can be understood from the description above, method 400 may beplasma free, which may avoid damage to the processed structure caused byplasma many conventional dry etching methods utilize.

Another advantage associated with method 400 may include isotropicetching of semiconductor materials, such as silicon, germanium, silicongermanium, or metal or metal-containing materials, such as molybdenum.Using silicon as an example, many etchants used in both wet and dryetching processes may only etch silicon at or from select crystal planesbut not the others. For example, many etchants may not etch or maysubstantially stop etching when contacted with (110), (111), etc.,crystal planes of silicon. As such, in the case of the substratefeatures formed of single-crystal silicon, the features may not beetched if the exposed surfaces correspond to one of the above mentionedcrystal planes of silicon. In the case of the substrate features formedof polysilicon, the etched profile may not be uniform because dependingon the orientation of the crystals, some may be etched while others maynot be etched. In contrast, the halogen-containing precursors used inthe present technology may etch the above mentioned semiconductormaterials from any crystal planes or towards any crystal directions.Therefore, whether the substrate features may be formed of single- orpolysilicon, the exposed surfaces may be etched uniformly. Further,because the halogen-containing precursors may etch the semiconductormaterials from any crystal planes or towards any crystal directions,method 400 may be utilized in lateral recessing of semiconductorfeatures, such as lateral recessing operations which may be performed inproducing V-NAND memory cells.

With reference to FIG. 7 exemplary operations of another method 700 areshown according to embodiments of the present technology. Different frommethod 400, method 700 may be implemented for etching of selectmetal-containing materials, which may include titanium, tantalum,tungsten, or one or more compounds thereof, such as titanium nitride,tantalum nitride, titanium tungsten, and so on. Method 700 may includeoperations similar to operations of method 400 to achieve finelycontrolled delivery of etching precursors and to achieve thin layeretching, including atomic or molecular layer etching, of selectmaterials.

Method 700 may include, at operation 705, flowing a halogen-containingprecursor into a processing region of a processing chamber where aprocessed structure may be positioned. The halogen-containing precursorsutilized for method 400 may also be utilized for method 700.Accordingly, the halogen-containing precursors flowed at operation 705may include one or more of noble gas compound precursors, interhalogenprecursors, fluorinating precursors, or other halogen-containingprecursors. The noble gas compound precursors may include one or morenoble gas halides, which may include xenon halides, such as xenonfluoride, krypton halides, such as krypton fluoride, or any othercompounds including a noble gas element and a halogen that may be usedor useful in semiconductor processes. Similar to method 400, method 700may utilize xenon difluoride as one of the halogen-containingprecursors, which may be vaporized first in a loading chamber, and thenflowed to the processing region of the processing chamber where theprocessed structure to be etched may be positioned. During theoperations of method 700, the pressure and/or temperature of the loadingchamber may be maintained at similar levels to those maintained for theloading chamber described above with reference to operations of method400. The interhalogen precursors may include one or more fluoridescontaining fluorine and one or more of chlorine, bromine, or iodine, oneor more chlorides containing chlorine and one or more of fluorine,bromine, or iodine, one or more bromides containing bromine or one ormore of fluorine, chlorine, or iodine, or other interhalogen precursorsthat may be used or useful in semiconductor processes. Some exemplaryinterhalogen precursors may include iodine fluoride, such as iodinemonofluoride, iodine trifluoride, iodine pentafluoride, iodineheptafluoride, and may further include chlorine fluoride, such aschlorine monofluoride, chlorine trifluoride, chlorine pentafluoride, andso on. The fluorinating precursors may include any of the noble gascompound precursors or the interhalogen precursors described above.

Method 700 may further include operation 710 similar to operation 410,during which the halogen-containing precursors may contact the exposedregions of the processed structure, which may include exposed regions ofselect metal-containing materials, such as titanium, tantalum, tungsten,or one or more compounds thereof, such as titanium nitride, tantalumnitride, titanium tungsten, and so on. Method 700 may also forming afilm on the surfaces of the exposed regions of the processed structureat operation 715, which may be similar to operation 415. Method 700 mayalso include pausing the flow of the halogen-containing precursors atoperation 720 by halting the flow of the halogen-containing precursors,and may further include purging the halogen-containing precursors thatmay not be adsorbed on the exposed surfaces of the processed structureat operation 725 such that only the halogen-containing precursors thatmay be adsorbed at the exposed surfaces of the processed structure mayremain in the processing region forming the halogen-containing precursorfilm, and any excess may be removed from the processing region. In someembodiments, only one or a few atomic or molecular layers of thehalogen-containing precursors may be adsorbed on the exposed surfaces ofthe processed structure.

Similar to method 400, method 700 may include additional controls overoperational conditions and such to control the thickness of thehalogen-containing precursor film. For example, at operation 705, only apredetermined or calculated amount or dosage of the halogen-containingprecursors may be flowed to the processing region. The flow rate of thehalogen-containing precursors may be maintained at relatively low levelsto facilitate uniform film formation. For example, the flow rate of thehalogen-containing precursors may be less than or bout 50 sccm inembodiments, and may be less than or about 45 sccm, less than or about40 sccm, less than or about 35 sccm, less than or about 30 sccm, lessthan or about 25 sccm, less than or about 20 sccm, less than or about 15sccm, less than or about 10 sccm, less than or about 5 sccm, less thanor about 3 sccm, less than or about 1 sccm, or less. Additionally, theflow of the halogen-containing precursors may be pulsed for time periodsof less than or about 30 seconds in embodiments, and may be pulsed fortime periods of less than or about 25 seconds, less than or about 20seconds, less than or about 15 seconds, less than or about 10 seconds,less than or about 5 seconds, less than or about 2 seconds, or less.Between each of the pulsed flow or delivery, the flow or delivery of thehalogen-containing precursors may be paused for less than or about 30seconds in embodiments, and may be paused for time periods of less thanor bout 25 seconds, less than or about 20 seconds, less than or about 15seconds, less than or about 10 seconds, less than or about 5 seconds,less than or about 2 seconds, or less. The flow rate and pulsing may becombined for any of the listed numbers. For example, the flow rate ofthe halogen-containing precursors may be below or about 10 sccm and maybe delivered in pulses from about 5 to about 10 seconds in embodiments,depending on the desired thickness of the film formed.

The pressure of the processing region of the processing chamber may bemaintained at relatively low levels, similar to the pressure levelsmaintained during operations of method 400. In some embodiments, thepressure of the processing region may be maintained below or about 50Torr in embodiments. The pressure may be maintained below or about 40Torr, and may be maintained below or about 30 Torr, below or about 20Torr, below or about 15 Torr, below or bout 10 Torr, below or about 5Torr, below or about 4 Torr, below or about 3 Torr, below or bout 2Torr, below or about 1 Torr, below or about 800 mTorr, below or about600 mTorr, below or about 400 mTorr, below or about 200 mTorr, below orabout 100 mTorr, below or bout 80 mTorr, below or about 60 mTorr, belowor about 40 mTorr, below or about 20 mTorr, below or about 10 mTorr,below or about 5 mTorr, below or about 2 mTorr, below or about 1 mTorr,or lower. Maintaining a relatively low pressure inside the processingchamber may facilitate even adsorption and uniform film formation by thehalogen-containing precursors, and in some embodiments, to facilitateatomic or molecular layer adsorption of the halogen-containingprecursors.

Although many operational conditions for method 700 may be kept to besimilar to those for method 400, the temperature in the processingregion or at the substrate level may be maintained at an elevated levelduring method 700 as compared to that of method 400 so as to allow forselective etching of titanium, tantalum, tungsten, or one or morecompounds thereof, such as titanium nitride, tantalum nitride, titaniumtungsten, and so on. In some embodiments, the temperature of theprocessing region or at the substrate level may be maintained betweenbout 0° C. and about 400° C. in embodiments. The temperature may bemaintained above or bout 5° C., and may be maintained above or about 10°C., above or about 15° C., above or about 20° C., above or about 25° C.,above or about 30° C., above or about 50° C., above or about 75° C.,above or about 100° C., above or about 150° C., above or about 200° C.,above or about 250° C., above or about 300° C., above or about 350° C.,or higher. Maintaining the temperature of the processing region or thesubstrate at relatively high temperature may increase the etch rate oftitanium, tantalum, tungsten, or one or more compounds thereof, such astitanium nitride, tantalum nitride, titanium tungsten. However,relatively high operational temperature may also decrease theselectivity of the halogen-containing precursors towards thesematerials. Depending on the particular application, the temperature ofthe processing region may be maintained between about room temperatureand about 300° C. to achieve desired etch rate as well as desiredselectivity.

Once a desired thickness of the halogen-containing precursor film may beadsorbed on the exposed regions of the processed structure, method 700may then proceed to operation 730 to etch select materials at theexposed regions of the processed structure. The interaction between theadsorbed halogen-containing precursors with titanium, tantalum,tungsten, titanium nitride, tantalum nitride, or titanium tungsten mayproduce one or more volatile substances, which may then be removed fromthe processing chamber. The volatile byproducts produced may includehalides of titanium, tantalum, or tungsten, such as fluorides oftitanium, tantalum, or tungsten. The volatile byproducts produced mayfurther include a noble gas or a halogen, which may be captured andrecycled to produce additional halogen-containing precursors, asdescribed below.

Depending on the thickness or amount of the halogen-containingprecursors adsorbed, an etched thickness of less than or about 5 nm maybe achieved. In some embodiments, an etching or removal thickness ofless than or about 4 nm, less than or about 3 nm, less than or bout 2nm, less than or about 1 nm, less than or about 9 Å, less than or about8 Å, less than or bout 7 Å, less than or about 6 Å, less than or about 5Å, less than or about 4 Å, less than or bout 3 Å, less than or about 2Å, or less in embodiments, down to a few molecules of removal may beachieved. In some embodiments, the removal may be at least about 5 Å,and may be between about 5 Å and about 5 nm of removal, or between about10 Å and about 2 nm of removal. In some embodiments, method 700 may berepeated for several cycles to achieve a greater overall removalthickness. In some embodiments, method 700 may be repeated for at leasttwo cycles, and may be repeated for at least about 3 cycles, at leastabout 5 cycles, at least bout 8 cycles, at least about 10 cycles, atleast about 20 cycles, at least about 50 cycles, at least bout 100cycles, or more. The number of cycles may be dependent on the amount ofremoval provided by each cycle.

Method 700 may have a selectivity towards titanium, tantalum, tungsten,titanium nitride, tantalum nitride, or titanium tungsten over siliconnitride, silicon carbide, silicon oxide, thermal oxide, or lowtemperature oxide of greater than or about 50:1, greater than or about100:1, greater than or about 150:1, greater than or about 200:1, orhigher depending on the operating conditions. Method 700 may also have asimilar selectivity towards titanium, tantalum, tungsten, titaniumnitride, tantalum nitride, or titanium tungsten over gold or copper.Other materials commonly used in semiconductor processing that method700 may not etch, or may have a close to infinite selectivity over, evenat elevated temperatures may include aluminum, nickel, chrome, platinum,gallium, hafnium, aluminum nitride, gallium arsenide, select oxides,such as PZT, magnesium oxide, zinc oxide, hafnium oxide, titanium oxide,aluminum oxide, zirconium dioxide, and so on. Method 700 may furtherhave high selectivity over select polymers or organic compounds commonlyused in semiconductor processing, such as photoresists, PDMS(polydimethylsiloxane), C₄F₈, silica glass, dicing tape, PP(polypropylene), PEN (polyethylene naphthalate), PET (polyethyleneterephthalate), ETFE (ethylene tetrafluoroethylene), acrylic, and so on.

It should be noted that although method 400 and method 700 are describedas separate methods, method 700 may also be performed to etch or removethe semiconductor materials that method 400 may be performed to etch orremove. Given the elevated temperature, method 700 may yield greateretch rates as compared to method 400. However, method 400 may yieldimproved selectivity. Depending on the particular application, if thestructure to be processed containing exposed regions of materials may beetched by both method 400 and method 700, then method 700 may beperformed. For example, if the materials to be removed include one ofthe metal-containing materials etched by method 700, such as titanium,titanium nitride, tantalum, tantalum nitride, tungsten, or titaniumtungsten, in addition to the semiconductor materials etched by method400, such as silicon, germanium, or silicon germanium, or themetal-containing materials etched by method 400, such as molybdenum,then method 700 may be performed to remove the semiconductor materialsas well as the metal-containing materials. If in some embodiments, thesemiconductor materials or the metal-containing materials may be removedat different operations, then the temperature in the processing regionor at the substrate level may be adjusted accordingly to achieve desiredremoval using either method 400 or method 700. Alternatively, thesubstrate may be processed at different processing chambers maintainedat different temperatures, with one at room temperature for method 400and one at elevated temperature for method 700.

With reference to FIG. 8, exemplary operations of another method 800 areshown according to embodiments of the present technology. Method 800 mayinclude operations 805-830 similar to or the same as operations 405-430of method 400 or operations 705-730 of method 700, depending on theparticular materials to be removed. In some embodiments, operations805-830 may be similar to operations 405-430 for etching semiconductormaterials. In some embodiments, operations 805-830 may be similar tooperations 705-730 for etching select metal-containing materials and/orsemiconductor materials.

Method 800 may include, at operation 805, flowing a firsthalogen-containing precursor into a processing region of a processingchamber where a processed structure may be positioned. The firsthalogen-containing precursor may include one or more of any of thehalogen-containing precursors described above with reference to method400 and method 700. Accordingly, the first halogen-containing precursorflowed at operation 805 may include one or more of noble gas compoundprecursors, interhalogen precursors, fluorinating precursors, or otherhalogen-containing precursors. The noble gas compound precursors mayinclude one or more noble gas halide, which may include xenon halides,such as xenon fluoride, krypton halides, such as krypton fluoride, orany other compounds including a noble gas element and a halogen that maybe used or useful in semiconductor processes. Similar to method 400 andmethod 700, method 800 may utilize xenon difluoride as the firsthalogen-containing precursor. The interhalogen precursors may includeone or more fluorides containing fluorine and one or more of chlorine,bromine, or iodine, one or more chlorides containing chlorine and one ormore of fluorine, bromine, or iodine, one or more bromides containingbromine or one or more of fluorine, chlorine, or iodine, or otherinterhalogen precursors that may be used or useful in semiconductorprocesses. Some exemplary interhalogen precursors may include iodinefluoride, such as iodine monofluoride, iodine trifluoride, iodinepentafluoride, iodine heptafluoride, and may further include chlorinefluoride, such as chlorine monofluoride, chlorine trifluoride, chlorinepentafluoride, and so on. The fluorinating precursors may include any ofthe noble gas compound precursors or the interhalogen precursorsdescribed above.

Method 800 may further include operation 810, during which the firsthalogen-containing precursor may contact the exposed regions of theprocessed structure, and may form a film on the exposed surfaces of theprocessed structure at operation 815. Method 800 may also includepausing the flow of the first halogen-containing precursor at operation820 by halting the flow of the first halogen-containing precursor, andmay further include purging the first halogen-containing precursor thatmay not be adsorbed on the exposed surfaces of the processed structureat operation 825 such that only the first halogen-containing precursorthat may be adsorbed at the exposed surfaces of the processed structuremay remain in the processing region forming the first halogen-containingprecursor film, and any excess may be removed from the processingregion. In some embodiments, only one or a few atomic or molecularlayers of the first halogen-containing precursor may be adsorbed on theexposed surfaces of the processed structure. Similar to method 400 andmethod 700, method 800 may further implement controls over the flow rateof the first halogen-containing precursor, the temperature and/orpressure of the loading chamber of the first halogen-containingprecursor (if utilized), the temperature and/or pressure of theprocessing region of the chamber where the processed structure may bepositioned, and/or other operational parameters, to obtain a desiredthickness of the film of the first halogen-containing precursor, whichmay be one or a few atomic or molecular layers of the firsthalogen-containing precursor in some embodiments. Once the desiredthickness of the first halogen-containing precursor film may be formed,method 800 may then proceed to operation 830 to etch select materials atthe exposed regions of the processed structure, which may produce one ormore volatile etch byproducts.

As mentioned above, certain etch byproducts may be collected andrecycled to generate halogen-containing precursors. In some embodiments,a noble gas compound precursor may be used during operations 805-830,then one of the volatile byproducts generated may include a noble gas,which may be collected at operation 835. For example, when xenondifluoride may be used as the first halogen-containing precursor duringoperation 805-830, xenon gas may be produced at operation 830 and may becollected at operation 835. In some embodiments, an interhalogenprecursor may be used during operations 805-830, then one of thevolatile byproducts generated may include a gas of one of the halogenelements forming the interhalogen, such as the element having arelatively lower electronegativity compared to the other element formingthe interhalogen. The gas of the halogen element having the relativelylow electronegativity may also be collected at operation 835. Forexample, when a chlorine fluoride may be used at the firsthalogen-containing precursor during operation 805-830, chlorine gas maybe produced at operation 830 and may be collected at operation 835.

The noble gas and/or the halogen gas collected at operation 835 may bedelivered into a processing chamber or system at operation 840 to mixwith a halogen-containing plasma, such as fluorine-containing plasma,which may include a plasma formed from nitrogen trifluoride. Atoperation 845, a second halogen-containing precursor may be formedthrough the reaction between the collected gas and thehalogen-containing precursor. At operation 850, the secondhalogen-containing precursor may then be flowed back to the processingregion for etching exposed regions of the processed structure, similarto how the first halogen-containing precursor may be flowed to theprocessing region for etching the exposed regions of the processedstructure in operations 805-830. In some embodiments, the secondhalogen-containing precursor may be flowed back to the same processingregion for continued etching of the processed structure. In someembodiments, the second halogen-containing precursor may be flowed to adifferent processing chamber for etching a different processedstructure. In some embodiments, the second halogen-containing precursorgenerated may be preserved for later use. In the case of xenondifluoride, the xenon difluoride generated at step 845 may be collectedby increasing the chamber pressure and/or lowering the chambertemperature such that xenon difluoride solid may be formed andcollected. By collecting the noble gas or the halogen gas and generatingadditional halogen-containing precursor therefrom, method 800 may bemore economical than conventional etching methods where byproducts maysimply be discharged.

In some embodiments, the processing chamber for generating the secondhalogen-containing precursor may be the same as the processing chamberin which operations 805-830 may be performed. The processing chamber mayinclude a remote plasma region, such as the capacitively-coupled plasma(CCP) region 215 described above with reference to FIG. 2, which may befluidly connected with but separate from the processing region where theprocessed structure may be positioned. The plasma powers utilized may berelative low so as to prevent damage to structures on the processedstructure. The plasma power in the CCP region may be at least about 50W, and may be greater than or about 100 W, greater than or about 150 W,greater than or about 200 W, greater than or about 250 W, greater thanor about 300 W, greater than or bout 350 W, greater than or about 400 W,greater than or about 450 W, greater than or about 500 W, or more inembodiments.

In some embodiments, the processing chamber for generating the secondhalogen-containing precursor using plasma may be a different chamberseparated from but fluidly connected with the processing chamber inwhich operations 805-830 may be performed. In some embodiments, thesecond halogen-containing precursor may be generated using a remoteplasma system, such as the RPS 201 discussed above with reference toFIG. 2. When using a separate chamber or system for forming the secondhalogen-containing precursor, the plasma power utilized by the separatechamber or system may be at least about 500 W, and may be greater thanor about 1000 W, greater than or about 1500 W, greater than or about2000 W, greater than or about 2500 W, greater than or about 3000 W,greater than or about 3500 W, greater than or about 4000 W, or more, tofacilitate the dissociation of the fluorine-containing precursors.

Generating the second halogen-containing precursor using a separatechamber or system may limit or prevent any plasma that may be flowedinto the processing region, which may damage the substrate features andcause unevenness in the etched profile. It may also allow for moreprecise control of the halogen-containing precursor flowed towards theprocessed structure so as to achieve thin layer etching, such as atomicor molecular layer etching. In addition, because plasma may be used informing the second halogen-containing precursor, the temperature of thesecond halogen-containing precursor formed may be relatively high.Forming the second halogen-containing precursor in a separate chamber orsystem may also allow the second halogen-containing precursor to becooled to a desired temperature before being flowed to the processingregion at operation 850.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology. Additionally, methods orprocesses may be described as sequential or in steps, but it is to beunderstood that the operations may be performed concurrently, or indifferent orders than listed.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a precursor” includes aplurality of such precursors, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

1. An etching method comprising: flowing a halogen-containing precursorinto a processing region of a semiconductor processing chamber;contacting an exposed region of a semiconductor material with thehalogen-containing precursor such that the halogen-containing precursoris adsorbed on a surface of the exposed region of the semiconductormaterial; forming a film of the halogen-containing precursor of apredetermined thickness on the surface of the exposed region of thesemiconductor material; pausing the flow of the halogen-containingprecursor into the processing region of the semiconductor processingchamber; and etching the exposed region of the semiconductor materialwith the adsorbed halogen-containing precursor, wherein the adsorbedhalogen-containing precursor produces a fluoride of the semiconductormaterial.
 2. The etching method of claim 1, further comprising purgingthe halogen-containing precursor not adsorbed on the surface of theexposed region of the semiconductor material.
 3. The etching method ofclaim 1, wherein the film of the halogen-containing precursor formed onthe surface of the exposed region of the semiconductor materialcomprises an atomic layer of the halogen-containing precursor.
 4. Theetching method of claim 1, wherein etching the exposed region of thesemiconductor material comprises etching isotropically the exposedregion of the semiconductor material.
 5. The etching method of claim 1,wherein the adsorbed halogen-containing precursor further produces anoble gas.
 6. The etching method of claim 1, wherein thehalogen-containing precursor comprises at least one of a noble gascompound precursor, an interhalogen precursor, or a fluorinatingprecursor.
 7. The etching method of claim 1, wherein the semiconductormaterial comprises at least one of silicon, germanium, or a compoundthereof.
 8. The etching method of claim 1, wherein a temperature of thesubstrate is maintained at about room temperature.
 9. The etching methodof claim 1, wherein the etching method is repeated for at least twocycles, and wherein a thickness of the semiconductor material etchedduring each cycle is between about 5 Å and about 50 Å.
 10. The etchingmethod of claim 1, wherein the etching method has a selectivity towardthe semiconductor material to a metal-containing material greater thanor bout 50:1, and wherein the metal-containing material comprises atleast one of titanium, titanium nitride, tantalum, tantalum nitride,tungsten, or titanium tungsten.
 11. The etching method of claim 1,wherein a pressure within the semiconductor processing chamber ismaintained between about 5 mTorr and about 50 Torr.
 12. An etchingmethod comprising: flowing a halogen-containing precursor into aprocessing region of a semiconductor processing chamber; contacting anexposed region of a metal-containing material with thehalogen-containing precursor such that the halogen-containing precursoris adsorbed on a surface of the exposed region of the metal-containingmaterial; forming a film of the halogen-containing precursor on thesurface of the exposed region of the metal-containing material; pausingthe flow of the halogen-containing precursor into the processing regionof the semiconductor processing chamber; and etching the exposed regionof the metal-containing material with the adsorbed halogen-containingprecursor, wherein the adsorbed halogen-containing precursor produces afluoride of the metal-containing material.
 13. The etching method ofclaim 12, further comprising purging the halogen-containing precursornot adsorbed on the surface of the exposed region of themetal-containing material such that an atomic layer of thehalogen-containing precursor is produced on the surface of the exposedregion of the metal-containing material.
 14. The etching method of claim12, wherein a temperature of the substrate is maintained between aboutroom temperature and about 300° C.
 15. The etching method of claim 12,wherein the metal-containing material comprises at least one ofmolybdenum, titanium, titanium nitride, tantalum, tantalum nitride,tungsten, or titanium tungsten.
 16. The etching method of claim 12,wherein the halogen-containing precursor comprises XeF₂.
 17. The etchingmethod of claim 12, further comprising: contacting an exposed region ofa semiconductor material with the halogen-containing precursor such thatthe halogen-containing precursor is adsorbed on a surface of the exposedregion of the semiconductor material; forming a film of thehalogen-containing precursor on the surface of the exposed region of thesemiconductor material; pausing the flow of the halogen-containingprecursor into the processing region of the semiconductor processingchamber; and etching the exposed region of the semiconductor materialwith the adsorbed halogen-containing precursor on the surface of theexposed region of the semiconductor material, wherein the adsorbedhalogen-containing precursor produces a fluoride of the semiconductormaterial.
 18. An etching method comprising: flowing a firsthalogen-containing precursor into a processing region of a semiconductorprocessing chamber, wherein the first halogen-containing precursorcomprises a noble gas compound precursor; contacting an exposed regionof a semiconductor material with the first halogen-containing precursorsuch that the first halogen-containing precursor is adsorbed on asurface of the exposed region of the semiconductor material; etching theexposed region of the semiconductor material with the adsorbed firsthalogen-containing precursor, wherein the adsorbed firsthalogen-containing precursor produces a gaseous byproduct; and forming asecond halogen-containing precursor from the gaseous byproduct usingplasma.
 19. The etching method of claim 18, further comprising: flowingthe second halogen-containing precursor into the processing region ofthe semiconductor processing chamber; contacting the exposed region ofthe semiconductor material with the second halogen-containing precursorsuch that the second halogen-containing precursor is adsorbed on thesurface of the exposed region of the semiconductor material; and etchingthe exposed region of the semiconductor material with the adsorbedsecond halogen-containing precursor, wherein the adsorbed secondhalogen-containing precursor produces a fluoride of the semiconductormaterial.
 20. The etching method of claim 18, wherein the gaseousbyproduct comprises at least one of a noble gas or a halogen gas.